[Technical Field]
[0001] The present teaching relates to a transmission, and particularly relates to a transmission
capable of performing seamless shift up.
[0002] In a known transmission having shift gears, a slider provided on a power transmission
shaft (an input shaft or an output shaft) moves in the axial direction in order to
change speed stages. As the slider moves in the axial direction, the slider is connected
to a shift gear provided on the power transmission shaft or the slider is disconnected
from a shift gear provided on the power transmission shaft. In the transmission, a
driving force may be interrupted due to disconnection between the slider and the shift
gear in shift up. As a scheme for shortening the time of interruption of the driving
force, for example, seamless shift up has been demanded.
[0003] For example, Patent Literature 1 discloses a transmission which is capable of performing
seamless shift up. The transmission of Patent Literature 1 is arranged so that, when
shifting up, two sliders are temporarily connected to the shift gear at the same time.
In the transmission of Patent Literature 1 in this state, a force in an axial direction
is generated to cancel the connection of one of the two sliders. With this arrangement,
seamless shift up is achieved without interrupting the transmission of power. In addition
to this, the transmission of Patent Literature 1 is provided with a cam biasing mechanism
that is provided on the outer circumference of each of an input shaft and an output
shaft so as to make contact with a cam surface on the slider. As the cam biasing mechanism
is pressed onto the cam surface of the slider, the slider receives a force acting
toward the shift gear. When a torque transmitted to the transmission is changed from
a drive torque to a coast torque, the slider can be moved by the cam biasing mechanism
from a meshed position where the drive torque is transmitted to a meshed position
where the coast torque is transmitted.
[Citation List]
[Patent Literatures]
[0004] [Patent Literature 1] International Publication No.
2020/250535
[Summary]
[Technical Problem]
[0005] In connection with the above, suppression of upsizing of the transmission has been
demanded.
[0006] An object of the present teaching is to suppress upsizing of a transmission that
is capable of performing seamless shift up.
[Solution to Problem]
(1) A transmission of an embodiment of the present teaching is arranged as described
below.
[0007] The transmission comprises an input shaft connected to a driving source and an output
shaft connected to a driving target, on the input shaft and the output shaft, shift
gears being provided to be each rotatable relative to the input shaft or the output
shaft and immovable in an axial direction of the input shaft and the output shaft,
the shift gears corresponding to speed stages in number, on the input shaft and the
output shaft, sliders being provided to be each rotatable together with the input
shaft or the output shaft, movable in the axial direction, and connectable to at least
one of the shift gears, two of the sliders being temporarily in a state of being connected
simultaneously with two of the shift gears when shifting up, and in the state of being
simultaneously connected, a force of canceling connection of one of the two sliders
being generated, at least one cam biasing mechanism being provided on at least one
of the input shaft or the output shaft and including a spring which exerts an elastic
force in a radial direction of the input shaft or the output shaft, at least one of
the sliders having a cam surface which makes contact with the cam biasing mechanism
so as to covert the elastic force exerted in the radial direction from the cam biasing
mechanism to a force exerted in the axial direction, the sliders being slide gears
each of which has a gear tooth surface meshed with a shift gear that is provided on
the input shaft or the output shaft, which is different from the shaft on which the
each of the sliders is provided, at least one of the slide gears having the cam surface
being moved on an outer circumferential surface of the input shaft or the output shaft
on which the at least one of the slide gears is provided, by the at least one cam
biasing mechanism that is formed on the input shaft or the output shaft on which the
at least one of the slide gears is provided, and the cam surface of the at least one
of the slide gears being arranged so that the maximum distance from the axial center
of the input shaft or the output shaft on which the at least one of the slide gears
is provided to the cam surface is shorter than the minimum distance from the axial
center to the gear tooth surface of the at least one of the slide gears.
[0008] According to this arrangement, at least one of the sliders has a cam surface. Alternatively,
each of all sliders may have the cam surface. Each of the sliders is a slide gear
having a gear tooth surface meshed with at least one shift gear. The slide gear functions
as a slider and a gear meshed with a shift gear at a gear tooth surface. In this way,
a gear meshed with a shift gear at a gear tooth surface and a slider are not independent
from each other. On the other hand, the slider of Patent Literature 1 is not a slide
gear, and the slider is provided on each of an input shaft and an output shaft, in
addition to a gear meshed with a shift gear at a gear tooth surface. On this account,
in the transmission of the present invention, the input shaft and the output shaft
can be arranged to be short as compared to Patent Literature 1.
[0009] At least one of the slide gears having the cam surface is moved on an outer circumferential
surface of the input shaft or the output shaft on which the at least one of the slide
gears is provided, by the at least one cam biasing mechanism that is formed on the
input shaft or the output shaft on which the at least one of the slide gears is provided.
The cam surface of the at least one of the slide gears is arranged so that the maximum
distance from the axial center of the input shaft or the output shaft on which the
at least one of the slide gears is provided to the cam surface is shorter than the
minimum distance from the axial center of the gear tooth surface to the at least one
of the slide gears. On this account, in the transmission of the present teaching,
the distance between the input shaft and the output shaft is short as compared to
Patent Literature 1 in which a slider is provided to move a cam biasing mechanism
provided on an outer circumference of each of an input shaft and an output shaft.
[0010] As described above, because in the transmission of the present teaching the lengths
of the input shaft and the output shaft and the distance between the input shaft and
the output shaft are arranged to be short, upsizing of the transmission can be suppressed
while seamless shift up is achieved.
[0011] (2) In addition to the arrangement (1) above, the transmission of the embodiment
of the present teaching may be arranged as described below.
[0012] At least part of a moving range of at least one of the slide gears provided on the
input shaft overlaps at least part of a moving range of at least one of the slide
gears provided on the output shaft, when viewed in a direction orthogonal to the axial
direction.
[0013] According to this arrangement, at least part of a moving range of at least one of
the slide gears provided on the input shaft overlaps at least part of a moving range
of at least one of the slide gears provided on the output shaft, when viewed in a
direction orthogonal to the axial direction. On this account, as compared to a case
where the moving range on the input shaft does not overlap the moving range on the
output shaft, the input shaft and the output shaft can be arranged to be short. In
particular, according to Patent Literature 1, at least part of a moving range of at
least one slider provided on the input shaft does not overlap at least part of a moving
range of at least one slider provided on the output shaft, when viewed in a direction
orthogonal to the axial direction of the input shaft and the output shaft. On this
account, in the transmission of the present teaching, the input shaft and the output
shaft can be arranged to be short as compared to Patent Literature 1.
[0014] As described above, because in the transmission of the present teaching the lengths
of the input shaft and the output shaft are further shortened, upsizing of the transmission
can be suppressed while seamless shift up is achieved.
[0015] (3) In addition to the arrangement (1) or (2) above, the transmission of the embodiment
of the present teaching may be arranged as described below.
[0016] Each of the at least one of the slide gears having the cam surface is arranged to
be moved in the axial direction by a shift fork, from a standby position where the
each slide gear is unconnected to a shift gear, and
the cam surface of the each slide gear is formed to move the each slide gear in a
direction away from the standby position in the axial direction, from the position
to which the each slide gear has been moved by the shift fork.
[0017] With this arrangement, without using the shift fork, the slide gear can be moved
away from the standby position from a position to which the slide gear has been moved
by the shift fork, by an elastic force of the cam biasing mechanism. In a transmission
capable of performing seamless shift up, as in Patent Literature 1, when a torque
transmitted to the transmission is changed from a drive torque to a coast torque,
the slider may be required to be moved from a drive meshed position to a coast meshed
position. The drive meshed position is a position where the drive torque is transmitted.
The coast meshed position is a position where the coast torque is transmitted. According
to the arrangement above, the requirement can be met by moving the slide gear from
the drive meshed position to the coast meshed position by the cam biasing mechanism,
after the slide gear is moved from the standby position to the drive meshed position
by the shift fork. On this account, the transmission of the present teaching is capable
of performing seamless shift up, while avoiding the upsizing of the transmission.
[0018] (4) In addition to any one of the arrangements (1) to (3) above, the transmission
of the embodiment of the present teaching may be arranged as described below.
[0019] Each of the at least one of the slide gears having the cam surface has a recess or
a protrusion to which the shift fork is fitted, and the cam surface of the at least
one of the slide gears is formed so that the maximum distance from the axial center
to cam surface is shorter than either the minimum distance from the axial center to
the recess or the maximum distance from the axial center to the protrusion.
[0020] According to this arrangement, the shift fork is fitted to the recess or the protrusion
of at least one slide gear having the cam surface. The cam surface of the slide gear
is formed so that the maximum distance from the axial center to the cam surface is
shorter than either the minimum distance from the axial center to the recess or the
maximum distance from the axial center to the protrusion. On this account, the transmission
can be downsized in the axial direction. Due to the above, because in the transmission
of the present teaching the lengths of the input shaft and the output shaft are further
shortened, upsizing of the transmission can be suppressed while seamless shift up
is achieved.
[0021] (5) In addition to any one of the arrangements (1) to (4) above, the transmission
of the embodiment of the present teaching may be arranged as described below.
[0022] Each of the at least one of the slide gears having the cam surface is formed so that
the cam surface of the each slide gear is positioned inside in the radial direction
of the gear tooth surface of the each slide gear, on a plane which at least partially
passes through the gear tooth surface of the each slide gear and is orthogonal to
the axial direction.
[0023] According to this arrangement, the cam surface is provided radially inside the gear
tooth surface on a plane that is orthogonal to the axial direction of the input shaft
or the output shaft on which at least one slide gear having the cam surface is provided
and passes through at least part of the gear tooth surface. To put it differently,
when viewed in a direction orthogonal to the axial direction, at least part of the
cam surface overlaps at least part of the gear tooth surface. On this account, as
compared to a case where the cam surface does not overlap the gear tooth surface,
the input shaft and the output shaft can be arranged to be short. Due to the above,
because in the transmission of the present teaching the lengths of the input shaft
and the output shaft are further shortened, upsizing of the transmission can be suppressed
while seamless shift up is achieved.
[0024] (6) In addition to any one of the arrangements (1) to (5) above, the transmission
of the embodiment of the present teaching may be arranged as described below.
[0025] The at least one of the slide gears having the cam surface is a switching slide gear
connectable to two of the shift gears provided on the same shaft as the at least one
of the slide gears, and speed stages corresponding to the two of the shift gears connected
to the switching slide gear are different from each other by at least two speed stages.
[0026] According to this arrangement, the switching slide gear provided on the input shaft
or the output shaft can be connected to two shift gears. Furthermore, the two shift
gears connected to the switching slide gear correspond to speed stages that are different
from each other by at least two speed stages. On this account, the transmission can
be arranged to achieve seamless shift up by utilizing the movement of the switching
slide gear having the cam surface. As compared to a transmission which is arranged
so that no switching slide gear is provided and a slide gear having a cam surface
is connectable to only one shift gear, it is possible to shorten the input shaft and
the output shaft. On this account, the transmission of the present teaching is capable
of performing seamless shift up, while improving the degree of freedom in designing
the transmission and avoiding the upsizing of the transmission.
[0027] (7) In addition to any one of the arrangements (1) to (6) above, the transmission
of the embodiment of the present teaching may be arranged as described below.
[0028] The slide gears include; two end portion slide gears which are provided at respective
ends in the axial direction and are provided on the same one of the input shaft and
the output shaft; and at least one slide gear which is provided on the input shaft
or the output shaft, which is different from the shaft on which the two end portion
slide gears are provided, and at least one of the two end portion slide gears has
the cam surface.
[0029] According to this arrangement, when two slide gears at the ends in the axial direction
of the slide gears are two end portion slide gears, the two end portion slide gears
are provided on the same shaft (the input shaft or the output shaft). Among the slide
gears, each slide gear different from the two end portion slide gears is provided
on a shaft different from the shaft on which the two end portion slide gears are provided.
At least one of the two end portion slide gears has the cam surface. On this account,
it is possible to realize a design with which seamless shift up is achieved by using
the end portion slide gear having the cam surface. In this way, the transmission of
the present teaching is capable of performing seamless shift up, while improving the
degree of freedom in designing the transmission and avoiding the upsizing of the transmission.
[0030] (8) In addition to any one of the arrangements (1) to (7) above, the transmission
of the embodiment of the present teaching may be arranged as described below.
[0031] Two of the shift gears, which are provided at respective ends in the axial direction,
are a first speed gear and a second speed gear.
[0032] As compared to the third and higher speed gears, a reaction force exerted to the
shift gear is large in the first speed gear and the second speed gear. On this account,
when the two shift gears at the both ends in the axial direction of the shift gears
are not the first speed gear and the second speed gear, the diameter of at least one
of the input shaft or the output shaft or the distance between the input shaft and
the output shaft must be long in order to suppress the deflection of at least one
of the input shaft or the output shaft, as compared to a case where the two shift
gears at the both ends in the axial direction of the shift gears are the first speed
gear and the second speed gear. According to the arrangement above, the diameter of
at least one of the input shaft or the output shaft and the distance between the input
shaft and the output shaft can be reduced as compared to a case where the two shift
gears at the both ends in the axial direction of the shift gears are not the first
speed gear and the second speed gear. Due to this, in the transmission of the present
teaching, while seamless shift up can be achieved, upsizing of the transmission can
be suppressed by further shortening the diameter of at least one of the input shaft
or the output shaft and the distance between the input shaft and the output shaft.
[0033] (9) In addition to the arrangement (8) above, the transmission of the embodiment
of the present teaching may be arranged as described below.
[0034] The number of the shift gears is six, and the shift gears include a third speed gear,
a fourth speed gear, a fifth speed gear, and a sixth speed gear in addition to the
first speed gear and the second speed gear, the slide gears include a fifth-speed
slide gear connectable to the fifth speed gear and a sixth-speed slide gear connectable
to the sixth speed gear, and the fifth-speed slide gear and the sixth-speed slide
gear are movable in the axial direction relative to each other, and the fifth speed
gear, the fifth-speed slide gear, the sixth-speed slide gear, and the sixth speed
gear are provided in this order on the same shaft, and the fifth-speed slide gear
has the cam surface.
[0035] According to this arrangement, the fifth-speed slide gear and the sixth-speed slide
gear connected to the fifth speed gear and the sixth speed gear provided on the same
shaft are independently provided. On this account, the transmission can be arranged
to achieve seamless shift up from the fifth speed stage to the sixth speed stage by
utilizing the movement of the fifth-speed slide gear having the cam surface and the
sixth-speed slide gear. Consequently, the transmission of the present teaching is
capable of performing seamless shift up, while improving the degree of freedom in
designing the transmission and avoiding the upsizing of the transmission.
[0036] (10) In addition to any one of the arrangements (1) to (9) above, the transmission
of the embodiment of the present teaching may be arranged as described below.
[0037] Except bearings used for providing the shift gears, there is no bearing between two
of the slide gears, which are provided on the same one of the input shaft and the
output shaft and adjacent to each other in the axial direction.
[0038] According to this arrangement, there is no bearing between two slide gears which
are provided on the same one of the input shaft and the output shaft and adjacent
to each other in the axial direction. This bearing excludes the bearings used for
providing the shift gears. On this account, in the transmission of the present teaching,
the input shaft and the output shaft are short as compared to a case where a bearing
is provided between two sliders that are on the same shaft and are adjacent to each
other in the axial direction. Consequently, the transmission of the present teaching
is capable of performing seamless shift up, while avoiding the upsizing of the transmission
by further shortening the input shaft and the output shaft.
<Definition of Transmission>
[0039] In the present teaching and the embodiments, a transmission is provided on at least
part of a power transmission path. The power transmission path is a path through which
power is transmitted from a driving source to a driving target. The transmission is
configured to change a transmission ratio. The transmission ratio is a ratio of rotation
speed of an input shaft of the transmission to rotation speed of an output shaft of
the transmission. The transmission may include a transmission device configured to
change a transmission ratio and a speed reducer configured to reduce the rotation
speed of power output from the transmission device, by means of gears, etc. The reduction
ratio of the speed reducer is unchanged. In the present teaching and the description,
the transmission is a multistage transmission which has plural shift gears that are
immovable in the axial direction of each of the input shaft and the output shaft and
correspond to speed stages in number, and which is configured to transmit power from
the input shaft to the output shaft through a shift gear correspond to a selected
speed stage. The transmission of the present teaching and the description does not
include a continuously variable transmission device having no shift gear. The transmission
of the present teaching and the embodiments may include an auxiliary transmission.
[0040] In the present teaching and the embodiments, the transmission is a multistage transmission.
In the present teaching and the embodiments, the transmission is a non-synchronous
transmission. In the present teaching and the embodiments, the transmission is a constant-mesh
transmission. In the present teaching and the embodiments, the transmission may be
an AMT (Automated Manual transmission) or an MT (Manual Transmission). The AMT is
also known as a semi-automatic transmission.
[0041] In the present teaching and the embodiments, the transmission is mounted on a vehicle,
for example. The vehicle on which the transmission is mounted may be a straddled vehicle
or an automobile. The straddled vehicle includes a motorcycle, a motor tricycle, a
four-wheeled buggy (ATV: All Terrain Vehicle), a snowmobile, and a personal watercraft,
for example. The motorcycle includes a scooter, an engine-equipped bicycle, a moped,
etc. In the present teaching and the embodiments, for example, the transmission may
be mounted on an apparatus such as an agricultural machine, which is not a vehicle.
<Definition of Driving Source>
[0042] In the present teaching and the embodiments, the driving source is a power source
for driving a driving target. The driving target is a vehicle, for example, and is
at least one driving wheel among at least one front wheel or at least one rear wheel,
when the transmission is mounted on a vehicle. The driving source may include an engine.
The driving source may include an engine and an electric motor. The driving source
may include an engine and an electric motor with a power generation function of generating
power by the output of the engine (or a generator and an electric motor). In this
case, the output of the engine may be used solely for the power generation.
<Definition of Axial Direction>
[0043] In the present teaching and the embodiments, the axial direction of each of the input
shaft and the output shaft is a direction in parallel to each of the rotational central
axis of the input shaft and the rotational central axis of the output shaft.
<Definition of Moving Range>
[0044] In the present teaching and the description, a moving range indicates a part in the
axial direction of the outer circumferential surface of each of the input shaft and
the output shaft, where plural slide gears move. The moving range is a part in the
axial direction of the outer circumferential surface of each of the input shaft and
the output shaft, where plural slide gears move, and is either a splined part where
grooves extending along the axial direction are formed in the outer circumferential
surface of each of the input shaft and the output shaft or a cylindrical part.
<Definition of Cam Biasing Mechanism and Cam Surface>
[0045] In the present teaching and the description, a cam biasing mechanism is formed on
either an input shaft or an output shaft on which a slide gear having a cam surface
is provided. The cam biasing mechanism may be any mechanism as long as it applies
an elastic force to the cam surface of the slide gear in the radial direction of the
shaft. The cam biasing mechanism may be formed entirely or partially by a spring.
The spring may be a coil spring or a disc spring. In the present teaching and the
description, the cam surface is provided on at least one slide gear and moves on the
outer circumferential surface of the input shaft or the output shaft on which the
slide gear is provided.
<Others>
[0046] In the present teaching and the embodiments, at least one of plural options encompasses
all conceivable combinations of the options. At least one of plural options may be
one of the options, some of the options, or all of the options. For example, at least
one of A, B, or C indicates only A, only B, only C, A and B, A and C, B and C, or
A, B, and C.
[0047] In the claims, when the number of a constituent feature is not clearly specified
and the constituent feature is expressed in a singular form in English, the number
of the constituent feature may be more than one in the present teaching. In the present
teaching, the number of the constituent features may be only one.
[0048] In the present teaching and the embodiments, terms "including", "comprising", "having",
and derivatives thereof are used to encompass not only listed items and equivalents
thereof but also additional items.
[0049] In the present teaching and the embodiments, the terms "mounted", "connected", "coupled",
and "supported" are used in broad sense. Specifically, not only direct attachment,
connection, coupling, and support but also indirect attachment, connection, coupling,
and support are included. Further, connected and coupled are not limited to physical
or mechanical connections and couplings. They also include direct or indirect electrical
connections and couplings.
[0050] Unless otherwise defined, all terms (technical and scientific terms) used in this
specification and claims indicate meanings typically understood by a person with ordinary
skill in the art in the technical field to which the present teaching belongs. Terms
such as those defined in commonly used dictionaries are to be interpreted as having
meaning that is consistent with their meaning in the context of the relevant art and
the present disclosure, and are not to be interpreted in an idealized or excessively
formal sense.
[0051] In the present teaching and the embodiments, the term "preferable" is non-exclusive.
The term "preferable" means "preferable but not limited to". In this specification,
an arrangement which is "preferable" exerts at least the above-described effects of
the arrangement of claim 1. In this specification, the term "may" is non-exclusive.
The term "may" indicate "may but not must". In this specification, an arrangement
which is explained by using the term "may" exerts at least the above-described effects
of the arrangement of claim 1.
[0052] In the present teaching and the embodiments, the preferred arrangements of the different
aspects described above may be variously combined. Before the embodiments of the present
teaching are detailed, it is informed that the present teaching is not limited to
the configurations and layout of elements described below and/or shown in drawings.
The present teaching is also applicable to embodiments other than the embodiments
described later. The present teaching may be implemented as an embodiment other than
the below-described embodiment. Furthermore, the present teaching may be implemented
by suitably combining below-described embodiments and modifications.
[Advantageous Effects]
[0053] The transmission of the present teaching is capable of performing seamless shift
up, while upsizing of the transmission is avoided.
[Brief Description of Drawings]
[0054]
FIG. 1 includes schematic diagrams illustrating a structure of a transmission of First
Embodiment.
FIG. 2 is a schematic diagram illustrating another structure of the transmission of
First Embodiment.
FIG. 3 includes schematic diagrams illustrating a structure of a transmission of Second
Embodiment.
FIG. 4 includes schematic diagrams illustrating movement of a slide gear in Third
Embodiment.
FIG. 5 includes schematic diagrams illustrating structures of slide gears of Fourth
Embodiment and Fifth Embodiment.
FIG. 6 is a schematic cross section of the slide gear of Sixth Embodiment.
FIG. 7 is a schematic cross section of a transmission of Seventh Embodiment.
FIG. 8 includes developed sectional views of a shift gear and a slide gear of the
transmission of Seventh Embodiment.
FIG. 9 is a schematic cross section of a transmission of Eighth Embodiment.
[Description of Embodiments]
[First Embodiment]
[0055] The following will describe a transmission 1 of First Embodiment of the present teaching
with reference to FIG. 1(a) and FIG. 1(b). FIG. 1(a) and FIG. 1(b) show two examples
of the transmission 1 of First Embodiment. The transmission 1 of First Embodiment
may be structurally different from those in FIG. 1(a) and FIG. 1(b).
[0056] The transmission 1 includes an input shaft 11 and an output shaft 12. The transmission
1 is configured to be able to transmit power of the input shaft 11 to the output shaft
12. The input shaft 11 is connected to a driving source 5. The output shaft 12 is
connected to a driving target 4. On the input shaft 11 and the output shaft 12, shift
gears 31, 32, 33, 34, 35, and 36 are provided to correspond to speed stages in number.
In other words, on the input shaft 11 or the output shaft 12, shift gears 31, 32,
33, 34, 35, and 36 are provided to correspond to speed stages in number. In the examples
shown in FIG. 1(a) and FIG. 1(b), the maximum number of speed stage is six. Each of
the shift gears 31, 32, 33, 34, 35, and 36 is provided to be rotatable relative to
the input shaft 11 or the output shaft 12 and immovable in the axial direction of
the input shaft 11 or the output shaft 12. The shift gears 31, 32, 33, 34, 35, and
36 are a first speed gear, a second speed gear, a third speed gear, a fourth speed
gear, a fifth speed gear, and a sixth speed gear, respectively. In FIG. 1, an arrow
X indicates the axial direction of each of the input shaft 11 and the output shaft
12. In the descriptions below, an axial direction indicates the axial direction of
each of the input shaft 11 and the output shaft 12.
[0057] On the input shaft 11 and the output shaft 12, sliders 41, 42, and 43 are provided.
Each of the sliders 41, 42, and 43 is provided to be rotatable together with the input
shaft 11 or the output shaft 12 and movable in the axial direction. Each of the sliders
41, 42, and 43 is connectable to at least one of the shift gears 31 to 36. Through
the shift gears 31 to 36 connected to the sliders 41, 42, and 43, power is transmitted
from the input shaft 11 to the output shaft 12. In the examples shown in FIG. 1(a)
and FIG. 1(b), the slider 41 having been moved is connected to the shift gear 31 or
the shift gear 33. The slider 42 having been moved is connected to the shift gear
32 or the shift gear 34. The slider 43 having been moved is connected to the shift
gear 35 or the shift gear 36. In the example shown in FIG. 1(a), the number of sliders
43 is one. In the example shown in FIG. 1(b), the number of sliders 43 is two, which
are sliders 43A and 43B.
[0058] Two of the sliders 41, 42, and 43 are arranged to be temporarily in a state of being
simultaneously connected to two shift gears among the shift gears 31 to 36, when shift
up is performed. To these two sliders, a force of canceling the connection of one
of the two sliders is exerted when the sliders are simultaneously connected to two
shift gears among the shift gears 31 to 36. On this account, the transmission 1 is
able to perform seamless shift up without interrupting the power. In the example shown
in FIG. 1(a), the transmission 1 is arranged to be able to seamlessly perform shift
up to the second speed, the third speed, and the fourth speed. In the example shown
in FIG. 1(b), the transmission 1 is arranged to be able to seamlessly perform shift
up to the second speed stage, the third speed stage, the fourth speed stage, the fifth
speed stage, and the sixth speed stage.
[0059] The transmission 1 includes at least one cam biasing mechanism 80. The at least one
cam biasing mechanism 80 is provided on at least one of the input shaft 11 or the
output shaft 12. Each cam biasing mechanism 80 includes a spring 81. The spring 81
exerts an elastic force in the radial direction of the input shaft 11 or the output
shaft 12.
[0060] At least one of the sliders 41, 42, and 43 has a cam surface 71. The at least one
slider having the cam surface 71 among the sliders 41, 42, and 43 will be collectively
termed a slider 40. In the examples shown in FIG. 1(a) and FIG. 1(b), each of the
two sliders 41 and 42 has the cam surface 71. In the example shown in FIG. 1(b), the
slider 43A among the two sliders 43 has the cam surface 71, too. The number of sliders
40 having the cam surface 71 may be one or more than one. The cam surface 71 is formed
on one of the two sliders simultaneously connected to two shift gears when shifting
up, to which a force of canceling the connection is applied. The cam surface 71 makes
contact with the cam biasing mechanism 80 so as to convert an elastic force exerted
in the radial direction from the cam biasing mechanism 80 to a force exerted in the
axial direction. The cam biasing mechanism 80 is provided for each slider 40 having
the cam surface 71.
[0061] The sliders 41, 42, and 43 are slide gears 41, 42, and 43. Each of the slide gears
41, 42, and 43 has a gear tooth surface 45 which is meshed with a shift gear that
is provided on the input shaft 11 or the output shaft 12, which is different from
the shaft on which that slide gear is provided. One gear tooth surface 45 is meshed
with one shift gear. Each of the slide gears 41, 42, and 43 has at least one gear
tooth surface 45 meshed with at least one shift gear. Each gear tooth surface 45 is
always meshed with one of the shift gears 31 to 36. In the examples shown in FIG.
1(a) and FIG. 1(b), the slide gear 41 has one gear tooth surface 45 meshed with the
shift gear 35, and the slide gear 42 has one gear tooth surface 45 meshed with the
shift gear 36. In the example shown in FIG. 1(a), the slide gear 43 has two gear tooth
surfaces 45 meshed with two shift gears 33 and 34, respectively. In the example shown
in FIG. 1(b), the slide gear 43A has one gear tooth surface 45 meshed with the shift
gear 33, and the slide gear 43B has one gear tooth surface 45 meshed with the shift
gear 34.
[0062] In the examples shown in FIG. 1(a) and FIG. 1(b), on the input shaft 11, a meshing
gear 21, a fifth speed gear 35, a slide gear 43, a sixth speed gear 36, and a meshing
gear 22 are provided in this order in the axial direction. Among these members, the
meshing gear 21 is closest to an end portion of the input shaft 11, with which the
driving source 5 is connected. On the input shaft 12, a first speed gear 31, a slide
gear 41, a third speed gear 33, a fourth speed gear 34, a slide gear 42, and a second
speed gear 32 are provided in this order in the axial direction. Among these members,
the first speed gear 31 is closest to an end portion of the input shaft 11, with which
the driving source 5 is connected. Each of the meshing gear 21 and the meshing gear
22 is arranged to be rotatable together with the input shaft 11 and immovable in the
axial direction.
[0063] At least one cam biasing mechanism 80 is formed on the input shaft 11 or the output
shaft 12, on which at least one slide gear 40 having the cam surface 71 is provided.
In other words, at least one cam biasing mechanism 80 is formed on at least one of
the input shaft 11 or the output shaft 12, on which at least one slide gear 40 having
the cam surface 71 is provided. The cam biasing mechanism 80 is provided for each
slide gear 40 having the cam surface 71. In the example shown in FIG. 1(a), two cam
biasing mechanisms 80 are formed on the output shaft 12 on which slide gears 41 and
42 are provided. In the example shown in FIG. 1(b), three cam biasing mechanisms 80
are formed on the input shaft 11 and the output shaft 12 on which slide gears 41,
42, and 43A are provided. At least one slide gear 40 having the cam surface 71 is
arranged to be moved on the outer circumferential surface of the input shaft 11 or
the output shaft 12 on which the at least one slide gear 40 is provided, by at least
one cam biasing mechanism 80. The cam surface 71 of the slide gear 40 is arranged
so that the maximum distance from the axial center (C11 or C12) of the input shaft
11 or the output shaft 12 on which the at least one slide gear 40 is provided to the
cam surface 71 is shorter than the minimum distance from the axial center (C11 or
C12) of the gear tooth surfaces 45 to the slide gears 41 and 42. The axial center
C11 is the axial center of the input shaft 11, whereas the axial center C12 is the
axial center of the output shaft 12. In the case of the cam surface 71 of the slide
gear 41 shown in FIG. 1(a), the cam surface 71 of the slide gear 41 is arranged so
that the maximum distance from the axial center C12 of the output shaft 12 on which
the slide gear 41 is provided to the cam surface 71 is shorter than the minimum distance
from the axial center C12 of the gear tooth surface 45 to the slide gear 41.
[0064] Because in the transmission 1 of First Embodiment the lengths of the input shaft
11 and the output shaft 12 and the distance between the input shaft 11 and the output
shaft 12 are arranged to be short, upsizing of the transmission 1 can be suppressed
while seamless shift up is achieved.
[0065] While the highest speed stage of the transmission 1 of First Embodiment shown in
FIG. 1(a) and FIG. 1(b) is the sixth speed stage, the highest speed stage of the transmission
1 of First Embodiment may not be the sixth speed stage but be any speed stage. The
arrangement of the shift gears of the transmission 1 of First Embodiment may be different
from the arrangement in the examples of FIG. 1(a) and FIG. 1(b). In the examples of
the transmission 1 shown in FIG. 1(a) and FIG. 1(b), on the input shaft 11 and the
output shaft 12, the first speed gear 31, the fifth speed gear 35, the third speed
gear 33, the fourth speed gear 34, the sixth speed gear 36, and the second speed gear
32 are provided in this order in the axial direction. For example, as in the example
of the transmission 1 shown in FIG. 2, on the input shaft 11 and the output shaft
12, the second speed gear 32, the sixth speed gear 36, the fourth speed gear 34, the
third speed gear 33, the first speed gear 31, and the fifth speed gear 35 may be provided
in order in the axial direction. In the example of FIG. 2, on the input shaft 11,
the meshing gear 22, the sixth speed gear 36, the slide gear 43, the first speed gear
31, and the meshing gear 25 are provided in this order in the axial direction. To
put it differently, on the input shaft 11 and the output shaft 12, the even-number-th
shift gears and the odd-number-th shift gears are provided in this order in the axial
direction, or the odd-number-th shift gears and the even-number-th shift gears are
provided in this order in the axial direction.
[0066] In the examples shown in FIG. 1(a) and FIG. 1(b), the two end portion slide gears
41 and 42 at the respective ends in the axial direction among the slide gears 41,
42, and 43 are on the same one of the input shaft 11 and output shaft 12. The sliders
41, 42, and 43 further include at least one slide gear 43 which is provided on a shaft
different from the input shaft 11 or the output shaft 12 on which the two end portion
slide gears 41 and 42 are provided. In the examples shown in FIG. 1(a) and FIG. 1(b),
each of the two end portion slide gears 41 and 42 has the cam surface 71. Alternatively,
only one of the two end portion slide gears 41 and 42 may have the cam surface 71.
[0067] In the examples shown in FIG. 1(a) and FIG. 1(b), two shift gears at the both ends
in the axial direction among the shift gears 31 to 36 are the first speed gear 31
and the second speed gear 32. While in the examples shown in FIG. 1(a) and FIG. 1(b)
the first speed gear 31 and the second speed gear 32 are both provided on the output
shaft 12, the disclosure is not limited to this arrangement. In the transmission 1
of First Embodiment, the first speed gear 31 and the second speed gear 32 may be provided
at the both ends in the axial direction among the shift gears 31 to 36 and provided
both on the input shaft 11. Because the two shift gears at the both ends in the axial
direction of the shift gears 31 to 35 are the first speed gear 31 and the second speed
gear 32, the diameter of at least one of the input shaft 11 or the output shaft 12
and the distance between the input shaft 11 and the output shaft 12 can be reduced
as compared to a case where the two shift gears at the both ends in the axial direction
of the shift gears 31 to 35 are not the first speed gear 31 and the second speed gear
32. On this account, the transmission 1 is capable of performing seamless shift up,
while avoiding the upsizing of the transmission 1.
[0068] In the transmission 1 of First Embodiment, the two shift gears at the both ends in
the axial direction among the shift gears 31 to 36 may not be the first speed gear
31 and the second speed gear 32 (see e.g., FIG. 2).
[0069] In the example shown in FIG. 1(b), the slide gears 41, 42, and 43 include a fifth-speed
slide gear 43 (43A) connectable with the fifth speed gear 35 and a sixth-speed slide
gear 43 (43B) connectable with the sixth speed gear 36. The fifth-speed slide gear
43 (43A) and the sixth-speed slide gear 43 (43B) are movable relative to each other
in the axial direction. The fifth speed gear 35, the fifth-speed slide gear 43 (43A),
the sixth-speed slide gear 43 (43B), and the sixth speed gear 36 are provided in this
order on the same shaft in the axial direction. The fifth-speed slide gear 43 (43A)
is provided with a cam surface 71. In the example shown in FIG. 1(b), the fifth speed
gear 35, the fifth-speed slide gear 43, the sixth-speed slide gear 43, and the sixth
speed gear 36 are provided on the input shaft 11. Alternatively, these members may
be provided on the output shaft 12. As the slide gears connected to the fifth speed
gear 35 and the sixth speed gear 36, respectively, are different, it is possible to
arrange the transmission 1 so that seamless shift up from the fifth speed stage to
the sixth speed stage is achieved by sliding of the fifth-speed slide gear 43 (43A)
having the cam surface 71 and the sixth-speed slide gear 43 (43B). On this account,
the transmission 1 shown FIG. 1(b) is capable of performing seamless shift up, while
improving the degree of freedom in designing the transmission 1 and avoiding the upsizing
of the transmission 1.
[0070] In the examples shown in FIG. 1(a) and FIG. 1(b), the slide gear 41, 42 having the
cam surface 71 is a switching slide gear. In the example shown in FIG. 1(b), the slide
gear 43 having the cam surface 71 is not a switching slide gear. A switching slide
gear can be connected with two shift gears among the shift gears 31 to 36, which are
provided on the same shaft (either the input shaft 11 or the output shaft 12) as the
switching slide gear. Furthermore, the two shift gears connected to the switching
slide gear correspond to speed stages that are different from each other by at least
two speed stages. In the examples shown in FIG. 1(a) and FIG. 1(b), the switching
slide gear 41 provided on the output shaft 12 can be connected to two shift gears
31 and 33. Furthermore, the switching slide gear 42 provided on the output shaft 12
can be connected to two shift gears 32 and 34. The speed stages to which the two shift
gears connected to the switching slide gear correspond may not be limited to the above,
on condition that the speed stages are different from each other by at least two speed
stages. Because a slide gear 40 having the cam surface 71 is a switching slide gear,
the transmission 1 can be arranged to achieve seamless shift up by utilizing the movement
of the switching slide gear 40 having the cam surface 71. As compared to a transmission
which is arranged so that no switching slide gear is provided and a slide gear having
a cam surface is connectable to only one shift gear, it is possible to shorten the
input shaft 11 and the output shaft 12. On this account, the transmission 1 shown
FIG. 1(a) and FIG. 1(b) is capable of performing seamless shift up, while improving
the degree of freedom in designing the transmission 1 and avoiding the upsizing of
the transmission 1.
[0071] The transmission 1 of First Embodiment may not include the switching slide gear.
In other words, the slide gear having the cam surface may be arranged to be connectable
to only one shift gear. Furthermore, all slide gears may be switching slide gears
as shown in the example of FIG. 1(a), or some slide gears may be switching slide gears
as shown in the example of FIG. 1(b).
[Second Embodiment]
[0072] The following will describe a transmission 1 of Second Embodiment of the present
teaching with reference to FIG. 3(a) and FIG. 3(b). In addition to the characteristics
of the transmission 1 of First Embodiment, the transmission 1 of Second Embodiment
has features described below.
[0073] The input shaft 11 has moving ranges 141 and 142 within which at least one slide
gear 41, 42 moves in the axial direction. The output shaft 12 has a moving range 143
within which at least one slide gear 43 moves in the axial direction. In FIG. 3(a)
and FIG. 3(b), the moving ranges 141, 142, and 143 are hatched by oblique lines. Slide
gears 41, 42, and 43 of Second Embodiment are provided so that at least part of the
moving ranges 141 and 142 of the at least one slide gear 41, 42 provided on the input
shaft 11 overlap at least part of the moving range 143 of at least one slide gear
43 provided on the output shaft 12, when viewed in a direction orthogonal to the axial
direction. In FIG. 3(a) and FIG. 3(b), an arrow Y indicates the direction orthogonal
to the axial direction of the input shaft 11 and the output shaft 12. In the example
shown in FIG. 3(a), part of the moving range 143 of the input shaft 11 overlaps part
of the moving range 141 and part of the moving range 142 of the output shaft 12 when
viewed in the direction orthogonal to the axial direction. In the example shown in
FIG. 3(b), part of the moving range 143 of the slide gear 43A (43) of the input shaft
11 overlaps part of the moving range 141 of the output shaft 12 when viewed in the
direction orthogonal to the axial direction, and part of the moving range 143 of the
slide gear 43B (43) of the input shaft 11 overlaps part of the moving range 142 of
the output shaft 12 when viewed in the direction orthogonal to the axial direction.
As compared to Patent Literature 1, the input shaft 11 and the output shaft 12 can
be arranged to be short in the transmission 1 of Second Embodiment.
[Third Embodiment]
[0074] The following will describe a transmission 1 of Third Embodiment of the present teaching
with reference to FIG. 4(a) to FIG. 4(c). Each of slide gears 40 shown in FIG. 4(a)
to FIG. 4(c) is one of the slide gears 41 and 42 in the example shown in FIG. 1(a)
and the slide gears 41, 42, and 43A in the example shown in FIG. 1(b). In addition
to the characteristics of the transmission 1 of First Embodiment, the transmission
1 of Third Embodiment has features described below.
[0075] Each of at least one slide gear 40 having a cam surface 71 is arranged to be moved
in the axial direction by a shift fork 110, from a standby position where the slide
gear is unconnected to a shift gear. The cam surface 71 of the slide gear 40 is formed
to move that slide gear 40 in a direction away from the standby position in the axial
direction, from the position to which the slide gear 40 has been moved by the shift
fork 110. In other words, the slide gear 40 having the cam surface 71 is moved in
a direction away from the standby position in the axial direction, from the position
to which the slide gear 40 has been moved by the shift fork 110, by an elastic force
of the cam biasing mechanism 80 exerted to the cam surface 71. FIG. 4(a) shows a state
in which the slide gear 40 is at the standby position. FIG. 4(b) shows a state in
which the slide gear 40 has been moved in the axial direction from the standby position,
by the shift fork 110. FIG. 4(c) shows a state in which the slide gear 40 has been
moved from the position shown in FIG. 4(b) by an elastic force of the cam biasing
mechanism 80 exerted to the cam surface 71. In the transmission 1 capable of performing
seamless shift up, for example, as described in the below-described Seventh Embodiment,
when a torque transmitted to the transmission 1 is changed from a drive torque to
a coast torque, the slide gear 40 may be required to be moved from a drive meshed
position to a coast meshed position that is far from the standby position as compared
to the drive meshed position. According to this arrangement, this requirement can
be met by moving the slide gear 40 from the drive meshed position to the coast meshed
position by the cam biasing mechanism 80, after the slide gear 40 is moved from the
standby position to the drive meshed position by the shift fork 110. On this account,
the transmission 1 of Third Embodiment is capable of performing seamless shift up,
while avoiding the upsizing of the transmission 1. It is noted that the state shown
in FIG. 4(c) is a state in which the slide gear 40 is at the coast meshed position.
It is noted that the state shown in FIG. 4(b) may be a state in which the slide gear
40 is at the drive meshed position. Alternatively, the state shown in FIG. 4(b) may
be a state in which the slide gear 40 is at a position between the drive meshed position
and the coast meshed position, when shift down is being performed.
[Fourth Embodiment and Fifth Embodiment]
[0076] The following will describe a transmission 1 of each of Fourth Embodiment and Fifth
Embodiment of the present teaching with reference to FIG. 5(a) and FIG. 5(b). FIG.
5(a) shows an arrangement of slide gears 40 of the transmission 1 of Fourth Embodiment.
FIG. 5(b) shows an arrangement of slide gears 40 of the transmission 1 of Fifth Embodiment.
Each of the slide gears 40 shown in FIG. 5(a) and FIG. 5(b) is one of the slide gears
41 and 42 in the example shown in FIG. 1(a) and the slide gears 41, 42, and 43A in
the example shown in FIG. 1(b). In addition to the characteristics of the transmission
1 of First Embodiment, the transmission 1 of each of Fourth Embodiment and Fifth Embodiment
has features described below.
[0077] In Fourth Embodiment, each of at least one slide gear 40 having a cam surface 71
has a recess 46 with which a shift fork 110 is engaged. The cam surface 71 of the
slide gear 40 is formed so that the maximum distance Da to the cam surface 71 from
the axial center C11, C12 of the input shaft 11 or the output shaft 12 on which that
slide gear 40 is provided is shorter than the minimum distance Db to the recess 46
from the axial center C11, C12 of the input shaft 11 or the output shaft 12 on which
that slide gear 40 is provided.
[0078] In Fifth Embodiment, each of at least one slide gear 40 having a cam surface 71 has
a protrusion 47 with which a shift fork 110 is engaged. The cam surface 71 of the
slide gear 40 is formed so that the maximum distance Da to the cam surface 71 from
the axial center C11, C12 of the input shaft 11 or the output shaft 12 on which that
slide gear 40 is provided is shorter than the maximum distance Dc to the protrusion
47 from the axial center C11, C12 of the input shaft 11 or the output shaft 12 on
which that slide gear 40 is provided. In Fourth Embodiment and Fifth Embodiment, the
transmission 1 can be downsized in the axial direction. Because in the transmission
1 of each of Fourth Embodiment and Fifth Embodiment the lengths of the input shaft
11 and the output shaft 12 are further arranged to be short, upsizing of the transmission
1 can be suppressed while seamless shift up is achieved.
[Sixth Embodiment]
[0079] The following will describe a transmission 1 of Sixth Embodiment of the present teaching
with reference to FIG. 6. A slide gear 40 shown in FIG. 6 is one of the slide gears
41 and 42 in the example shown in FIG. 1(a) and the slide gears 41, 42, and 43A in
the example shown in FIG. 1(b). In addition to the characteristics of the transmission
1 of First Embodiment, the transmission 1 of Sixth Embodiment has features described
below.
[0080] Each of at least one slide gear 40 having the cam surface 71 is formed such that
the cam surface 71 of that slide gear 40 is radially inside a gear tooth surface 45
of that slide gear 40 on a plane that passes through at least part of the gear tooth
surface 45 of that slide gear 40 and is orthogonal to the axial direction. A plane
S1 shown in FIG. 6 is an example of the plane that passes through the gear tooth surface
45 of the slide gear 40 and is orthogonal to the axial direction. In this arrangement,
when viewed in a direction orthogonal to the axial direction, at least part of the
cam surface 71 overlaps at least part of the gear tooth surface 45. On this account,
as compared to a case where the cam surface 71 does not overlap the gear tooth surface
45, the input shaft 11 and the output shaft 12 can be arranged to be short. Because
in the transmission 1 of Sixth Embodiment the lengths of the input shaft 11 and the
output shaft 12 are further arranged to be short, upsizing of the transmission 1 can
be suppressed while seamless shift up is achieved.
[Seventh Embodiment]
[0081] The following will describe a transmission 1 of Seventh Embodiment of the present
teaching with reference to FIG. 7 and FIG. 8. The transmission 1 of Seventh Embodiment
is a specific example of the transmission 1 of First Embodiment shown in FIG. 1(a).
The transmission 1 of Seventh Embodiment may have the arrangement of at least one
transmission 1 of Second Embodiment to Sixth Embodiment.
[0082] The transmission 1 is mounted on, for example, a vehicle (not illustrated) such as
a motorcycle. The vehicle includes a driving source 5 such as an engine, the transmission
1, a clutch 2, and a controller (not illustrated). The driving force generated by
the driving source 5 is transmitted to a wheel that is a driving target 4 (see FIG.
1(a)) through the clutch 2 and the transmission 1. The controller controls the driving
source 5, the transmission 1, and the clutch 2.
[0083] The transmission 1 is configured to be able to transmit power of the input shaft
11 to the output shaft 12. The ratio of the rotational speed of the input shaft 11
to the rotation speed of the output shaft 12 is termed a transmission ratio. The transmission
1 has plural speed stages (gear positions) that are different in transmission ratio.
The speed stage of the transmission 1 is changed by the controller. The vehicle may
include a shift operator (not illustrated) that is operated by the driver to change
the speed stage of the transmission 1. The controller changes the speed stage of the
transmission 1 in accordance with an operation of the shift operator. The controller
may be arranged to be able to automatically change the speed stage of the transmission
1 in accordance with, for example, the vehicle speed, when the shift operator is not
operated. The vehicle may not include a shift operator that is operated by the driver
to change the speed stage of the transmission 1.
[0084] The input shaft 11 is connected to the driving source 5 through the clutch 2. When,
for example, the driving source 5 is an engine, the input shaft 11 is connected to
the crankshaft of the engine. The clutch 2 is a friction clutch, for example, but
is not limited to this. However, the clutch 2 is not a dual clutch. In other words,
the transmission 1 is not a dual clutch transmission. The transmission 1 is an AMT
(Automated Manual Transmission). In other words, the controller is arranged to be
able to automatically change the power transmission ratio of the clutch 2 without
requiring an operation by the driver. The controller may control at least one of the
clutch 2 or the engine (driving source 5) when changing the speed stage of the transmission
1.
[0085] The input shaft 11 is supported by bearings 11a and 11b. The output shaft 12 is supported
by bearings 12a and 12b. At least one of the shift gears 31 to 36 may be supported
by the input shaft 11 or the output shaft 12 through a bearing. At least one of the
shift gears 31 to 36 may be supported by the input shaft 11 or the output shaft 12
without the intermediary of a bearing. Between two slide gears 41 and 42 provided
on the input shaft 11 and adjacent to each other in the axial direction, no bearing
is provided except bearings used for providing the shift gears 33 and 34.
[0086] As shown in FIG. 7, the transmission 1 includes three slide gears 41, 42, and 43.
The following will describe an arrangement in which the shift gears 31 to 36 are connected
to the slide gears 41, 42, and 43.
[0087] The slide gear 41 has dogs 51 that are provided at an end portion opposing the first
speed gear 31 in the axial direction. The first speed gear 31 has dogs 61 that are
connectable with the dogs 51 of the slide gear 41 by meshing therewith. The slide
gear 41 has dogs 53 that are provided at an end portion opposing the third speed gear
33 in the axial direction. The third speed gear 33 has dogs 63 that are connectable
with the dogs 53 of the slide gear 41 by meshing therewith. The slide gear 42 has
dogs 52 that are provided at an end portion opposing the second speed gear 32 in the
axial direction. The second speed gear 32 has dogs 62 that are connectable with the
dogs 52 of the slide gear 42 by meshing therewith. The slide gear 42 has dogs 54 that
are provided at an end portion opposing the fourth speed gear 34 in the axial direction.
The fourth speed gear 34 has dogs 64 that are connectable with the dogs 54 of the
slide gear 42 by meshing therewith. The slide gear 43 has dogs 55 that are provided
at an end portion opposing the fifth speed gear 35 in the axial direction. The fifth
speed gear 35 has dogs 65 that are connectable with the dogs 55 of the slide gear
43 by meshing therewith. The slide gear 43 has dogs 56 that are provided at an end
portion opposing the sixth speed gear 36 in the axial direction. The sixth speed gear
36 has dogs 66 that are connectable with the dogs 56 of the slide gear 43 by meshing
therewith.
[0088] As the slide gears 41, 42, and 43 are moved in the axial direction from the standby
position shown in FIG. 7, each of the slide gears 41, 42, and 43 is meshed with one
of the shift gears 31 to 36 adjacent to the each slide gear in the axial direction,
by means of the dogs. When one of the shift gears 31 to 36 is meshed with a slide
gear adjacent to the one shift gear in the axial direction by means of the dogs, power
is transmitted from the input shaft 11 to the output shaft 12 through that shift gear
and that slide gear. For example, when the first speed gear 31 is meshed with the
slide gear 41, the power from the input shaft 11 is transmitted to the gear 21, the
first speed gear 31, the slide gear 41, and then the output shaft 12 in order. The
speed stage of the transmission 1 in this case is the first speed stage. For example,
when the third speed gear 33 is meshed with the slide gear 41, the power from the
input shaft 11 is transmitted to the slide gear 43, the third speed gear 33, the slide
gear 41, and then the output shaft 12 in order. The speed stage of the transmission
1 in this case is the third speed stage. For example, when the fifth speed gear 35
is meshed with the slide gear 43, the power from the input shaft 11 is transmitted
to the slide gear 43, the fifth speed gear 35, the slide gear 41, and then the output
shaft 12 in order. The speed stage of the transmission 1 in this case is the fifth
speed stage. When none of the shift gears is meshed with a slide gear adjacent to
each shift gear in the axial direction, the transmission 1 is in a neutral state.
As the movement of the slide gears 41, 42, and 43 in the axial direction is controlled,
the speed stage of the transmission 1 is controlled. In other words, the slide gears
41, 42, and 43 are driven in the axial direction in order to change the speed stage.
[0089] The dogs 51 are aligned in the circumferential direction. The dogs 52 to 56 and 61
to 66 are also aligned in the circumferential direction. The dogs 51 to 56 of the
slide gears 41, 42, and 43 are dog teeth. In other words, the dogs 51 to 56 are formed
to protrude in the axial direction. The dogs 61 to 64 of the shift gears 31 to 34
are dog holes. The dogs 61 to 64 are concave in shape. In other words, the dogs 61
to 64 are dog holes that do not penetrate the shift gears 31 to 34 in the axial direction.
The dogs 61 to 64 may be dog holes penetrating the shift gears 31 to 36 in the axial
direction. The dogs 61 to 64 may be dog teeth. In this case, the dogs 51 to 54 may
be dog teeth or dog holes. The dogs 65 and 66 of the shift gears 35 and 36 are dog
teeth. The dogs 65 and 66 may be dog holes.
[0090] The following will describe common characteristics of the dogs (dog holes) 61 to
64 of the shift gears 31 to 34 and common characteristics of the dogs (dog teeth)
51 to 54 of the slide gears 41 and 42, by taking the dog 62 of the second speed gear
32 and the dog 52 of the slide gear 42 as an example. FIG. 8(a) to FIG. 8(e) are developed
sectional views of the second speed gear 32 and the slide gear 42. The up-down direction
in each of FIG. 8(a) to FIG. 8(e) indicates the circumferential direction about the
rotational central axis of the output shaft 12. The rotational direction of each of
the shift gear 32 and the slide gear 42 is an upward direction in FIG. 8(a) to FIG.
8(e). FIG. 8(a) shows a state in which the transmission 1 is at a speed stage different
from the second speed stage or at the neutral position. The arrows in FIG. 8(b) and
FIG. 8(c) show the direction of the torque generated in the shift gear 32. The arrows
in FIG. 8(d) and FIG. 8(e) show the rotational direction of the slide gear 42 relative
to the shift gear 32 and the rotational direction of the shift gear 32 relative to
the slide gear 42.
[0091] The dog (dog tooth) 52 has a drive meshing surface 57, a coast meshing surface 58,
and a release guide surface 59. In the axial direction, the drive meshing surface
57 is close to the tip of the teeth as compared to the coast meshing surface 58. The
drive meshing surface 57 is tilted in the circumferential direction relative to the
axial direction. The drive meshing surface 57 is tilted so that one end of the surface
close to the bottom of the teeth is on the downstream in the rotational direction
of the shift gear 32 and the slide gear 42 as compared to the other end of the surface
far from the bottom of the teeth. The drive meshing surface 57 may be formed to extend
along the axial direction. The coast meshing surface 58 is tilted in the circumferential
direction relative to the axial direction. The coast meshing surface 58 is tilted
so that one end of the surface close to the tip of the teeth is on the downstream
in the rotational direction of the shift gear 32 and the slide gear 42 as compared
to the other end of the surface far from the tip of the teeth. The coast meshing surface
58 may be formed to extend along the axial direction. The release guide surface 59
is aligned with the drive meshing surface 57 in the circumferential direction. The
release guide surface 59 is tilted in the axial direction relative to the circumferential
direction. The release guide surface 59 may be spiral in shape relative to the rotational
central axis of the output shaft 12, or may extend along the radial direction.
[0092] The dog (dog hole) 62 has a drive meshing surface 67, a coast meshing surface 68,
and a movement guiding surface 69. The tilt angle and the tilting direction of the
drive meshing surface 67 relative to the axial direction are identical with those
of the drive meshing surface 57 of the dog 52. The tilt angle and the tilting direction
of the coast meshing surface 68 relative to the axial direction are identical with
those of the coast meshing surface 58 of the dog 52. The movement guiding surface
69 is tilted in the axial direction relative to the circumferential direction. The
movement guiding surface 69 may be spiral in shape relative to the rotational central
axis of the output shaft 12, or may extend along the radial direction.
[0093] FIG. 8(b) shows a state in which the drive meshing surface 57 is in contact with
the drive meshing surface 67 and the dog 52 is meshed with the dog 62. This meshed
state will be referred to as a drive meshed state. The position in the axial direction
of the slide gear 42 when the slide gear 42 and the shift gear 32 are in the drive
meshed state will be referred to as the drive meshed position of the slide gear 42
relative to the shift gear 32. It is noted that the term "drive meshed position" is
used no matter whether the drive meshed state is established. When the transmission
1 transmits a drive torque with the second speed stage, the shift gear 32 and the
slide gear 42 are in the drive meshed state. The drive torque is a torque transmitted
from an engine to a wheel when the engine drives the wheel.
[0094] FIG. 8(c) shows a state in which the coast meshing surface 58 is in contact with
the coast meshing surface 68 and the dog 52 is meshed with the dog 62. This meshed
state will be referred to as a coast meshed state. In the coast meshed state, the
dogs 52 and 62 are deeply meshed with each other as compared to the drive meshed state.
The position in the axial direction of the slide gear 42 when the slide gear 42 and
the shift gear 32 are in the coast meshed state will be referred to as the coast meshed
position of the slide gear 42 relative to the shift gear 32. It is noted that the
term "coast meshed position" is used no matter whether the coast meshed state is established.
When the transmission 1 transmits a coast torque with the second speed stage, the
shift gear 32 and the slide gear 42 are in the coast meshed state. The coast torque
is a torque generated by the rotational inertia of the wheel and is exerted in the
direction opposite to the drive torque. The coast torque is a torque transmitted between
the engine and the wheel. The coast torque is generated when, for example, engine
braking is performed.
[0095] FIG. 8(d) shows a state in which an edge of the dog (dog tooth) 52 is in contact
with the movement guiding surface 69. As shown in FIG. 8(d), when the edge of the
dog 52 makes contact with the movement guiding surface 69 while the slide gear 42
rotates at a lower speed than the shift gear 32, the slide gear 42 receives a force
acting away from the shift gear 32. When the transmission 1 is at the second speed
stage and the torque transmitted to the transmission 1 is switched from the coast
torque to the drive torque, the slide gear 42 rotates at a lower speed than the shift
gear 32. Due to this, the meshing between the coast meshing surfaces 58 and 68 of
the slide gear 42 and the shift gear 32 is canceled, and the dog 52 of the slide gear
42 makes contact with the movement guiding surface 69 of the shift gear 32. The dog
52 moves along the movement guiding surface 69, and the slide gear 42 and the shift
gear 32 become in the drive meshed state. When the transmission 1 is at the second
speed stage and the torque transmitted to the transmission 1 is switched from the
drive torque to the coast torque, the slide gear 42 rotates at a speed higher than
the shift gear 32. As a result, the meshing between the drive meshing surfaces 57
and 67 of the slide gear 42 and the shift gear 32 is canceled. On account of the elastic
force exerted from the spring 81 of the cam biasing mechanism 80 in contact with the
cam surface 71, the slide gear 42 moves in a direction in which the slide gear 42
is further deeply meshed, with the result that the slide gear 42 and the shift gear
32 become in the coast meshed state.
[0096] FIG. 8(e) shows a state in which the edge of the dog (dog hole) 62 is in contact
with the release guide surface 59. As shown in FIG. 8(e), when the edge of the dog
62 makes contact with the release guide surface 59 while the slide gear 42 rotates
at a higher speed than the shift gear 32, the slide gear 42 receives a force acting
away from the shift gear 32. To put it differently, when the dog 62 makes contact
with the release guide surface 59, the force by which the meshing between the dogs
52 and 62 of the shift gear 32 and the slide gear 42 is canceled is generated in the
slide gear 42. As detailed later, the release guide surface 59 is used when the speed
stage is changed.
[0097] The dogs (dog holes) 61 to 64 may be different from one another in shape, as long
as they share the above-described common characteristics. At least two of or all of
the dogs 61 to 64 may be symmetrical in shape. The dogs (dog teeth) 51 to 54 may be
different from one another in shape. At least two of or all of the dogs 51 to 54 may
be symmetrical in shape. The dogs (dog teeth) 51 to 54 are different from the dogs
(dog teeth) 55 and 56 in shape. The dogs (dog teeth) 55 and 56 may be different in
shape, identical in shape, or symmetrical in shape. The dogs (dog teeth) 65 and 66
may be different in shape, identical in shape, or symmetrical in shape. The dogs (dog
teeth) 65 and 66 may be different from the dogs (dog teeth) 55 and 56 in shape, identical
in shape, or symmetrical in shape.
[0098] Each of the dogs 51 to 54 of the slide gears 41 and 42 has the release guide surface
59, whereas each of the dogs 61 to 64 of the shift gears 31 to 34 has the movement
guiding surface 69. Each of the dogs of the slide gears 41 and 42 may have both the
movement guiding surface and the release guide surface as in the dog of the slider
of Patent Literature 1. The dog 54 of the slide gear 42 may not have the release guide
surface 59. Each of the dogs 64 of the fourth speed gear 34 and the dogs 54 of the
slide gear 42 may not have the movement guiding surface. The shape of each of the
dogs 64 of the fourth speed gear 34 and the dogs 54 of the slide gear 42 may be identical
with the shape of each of the dogs 65 and 66 of the shift gears 35 and 36 and the
dogs 55 and 56 of the slide gear 43.
[0099] The transmission 1 is arranged so that, when shifting up, the transmission 1 is temporarily
in a double-meshed state where the two slide gears 41 and 42 are simultaneously meshed
with two of the shift gears 31 to 34 through dogs. In the temporal double-meshed state,
the two slide gears 41 and 42 are temporarily connected to two shift gears simultaneously.
For example, when shifting up from the first speed stage to the second speed stage,
the transmission 1 is temporarily in the double-meshed state where the two slide gears
41 and 42 are simultaneously meshed with the shift gears 31 and 32 through the dogs
51, 52, 61, and 62. When the slide gear 42 is meshed with the second speed gear 32
through the dogs 52 and 62, the slide gear 41 rotates at a higher speed than the first
speed gear 31. The transmission 1 is arranged so that the movement of the slide gear
41 in the axial direction toward the first speed gear 31 is restricted in this case.
As a result, the release guide surface 59 of the dog 51 of the slide gear 41 makes
contact with the dog 61 of the first speed gear 31 and hence the slide gear 41 moves
away from the first speed gear 31 in the axial direction. Due to this, the meshing
between the dog 51 of the slide gear 41 and the dog 61 of the first speed gear 31
is canceled. On this account, being different from the controller of the known transmission,
the controller is not required to control the clutch 2 and the engine in order to
reduce the pressing force generated in accordance with the power transmission between
the dog 51 of the slide gear 41 and the dog 61 of the first speed gear 31. As such,
the transmission 1 is arranged so that a force of canceling the meshing of the dogs
is generated in one of the two slide gears 41 and 42, when the double-meshed state
is established. The transmission 1 is therefore able to seamlessly perform shift up
to the second speed stage without blocking the power transmission. Likewise, the transmission
1 is able to seamlessly perform shift up to the third speed stage and the fourth speed
stage without blocking the power transmission. The transmission 1 is arranged so that
the double-meshed state is not established when shifting down.
[0100] The following will describe the common characteristics of the slide gears 41 and
42 apart from the dogs, by taking the slide gear 42 as an example. The slide gears
41 and 42 may be different from one another in shape, as long as they share the below-described
common characteristics. The slide gears 41 and 42 may be symmetrical in shape.
[0101] The slide gear 42 is spline-fitted to the output shaft 12. As shown in FIG. 7, in
the inner circumferential surface of the slide gear 42, four cam surfaces 71 and two
checking grooves 72 are formed. Each checking groove 72 is formed between two cam
surfaces 71 that are aligned in the axial direction. The checking grooves 72 may not
be formed. The slide gear 42 makes contact with a cam biasing mechanism 80 provided
on the output shaft 12. The cam biasing mechanism 80 makes contact with the four cam
surfaces 71 and the two checking grooves 72. The cam surface 71 of the slide gear
42 is separated from the dogs 52 and 54 of the slide gear 42 in the axial direction.
The cam biasing mechanism 80 simultaneously makes contact with two cam surfaces 71
aligned in the circumferential direction among the four cam surfaces 71. The number
of cam surfaces 71 formed to be aligned in the circumferential direction is not limited
to two, and may be three or more. The number of checking grooves 72 formed to be aligned
in the circumferential direction is not limited to two, and may be three or more.
The checking grooves 72 may be a single groove that is continuous in the circumferential
direction. The cam biasing mechanism 80 has a spring 81 which applies an elastic force
to the slide gear 42 outward in the radial direction of the output shaft 12.
[0102] The cam surface 71 is a slope surface tilted in the radial direction relative to
the axial direction. When the slide gear 42 moves in the axial direction, the cam
biasing mechanism 80 makes contact with the cam surface 71. The cam surface 71 is
configured to convert an elastic force exerted in the radial direction from the cam
biasing mechanism 80 to a force in the axial direction. When the cam biasing mechanism
80 makes contact with the cam surface 71, the elastic force of the spring 81 acts
as a force of pressing the slide gear 42 in the axial direction in which the checking
groove 72 moves away from the cam biasing mechanism 80. The checking groove 72 is
formed to allow the cam biasing mechanism 80 to be fitted thereto. When the transmission
1 is in neither the second speed stage nor the fourth speed stage, the cam biasing
mechanism 80 is fitted to the checking groove 72 of the slide gear 42.
[0103] The slide gears 41, 42, and 43 are connected to the shift forks 111, 112, and 113,
respectively. The shift forks 111, 112, and 113 are specific examples of the shift
fork 110 of Third Embodiment. The slide gears 41, 42, and 43 move in the axial direction
as the shift forks 111, 112, and 113 move in the axial direction. The shift forks
111, 112, and 113 are included in a shift mechanism in which the sliders 41, 42, and
43 are moved by the shift forks 111, 112, and 113. The shift mechanism includes an
unillustrated shift actuator that is controlled by the controller. As the controller
controls the shift actuator, the shift forks 111, 112, and 113 move in the axial direction.
The structure of the shift mechanism is not particularly limited. The shift mechanism
may be a mechanism including a shift drum, for example. To be more specific, for example,
parts of the shiftforks 111, 112, and 113 may be provided in grooves formed in the
shift drum, respectively. Alternatively, for example, parts of components connected
to the shift forks 111, 112, and 113 so as to move in the axial direction together
with the shift forks 111, 112, and 113 may be provided in grooves formed in the shift
drum. A mechanism in which the shift drum is rotated by the shift actuator is not
particularly limited. The shift mechanism may not include a shift drum. The transmission
1 may be a sequential manual transmission. In other words, the transmission 1 may
be arranged so that, when the speed stage (gear position) is changed, the speed stage
is changeable to only a speed stage that is adjacent to the speed stage before the
change in terms of the transmission ratio.
[Eighth Embodiment]
[0104] The following will describe a transmission 1 of Eighth Embodiment of the present
teaching with reference to FIG. 9. The transmission 1 of Eighth Embodiment is a specific
example of the transmission 1 of First Embodiment shown in FIG. 1(b). The transmission
1 of Eighth Embodiment may have the arrangement of at least one transmission 1 of
Second Embodiment to Sixth Embodiment. The following will describe arrangements which
are different from those of Seventh Embodiment.
[0105] As shown in FIG. 9, the transmission 1 includes four slide gears 41, 42, 43A, and
43B. The slide gears 43A and 43B are specific examples of the slide gears 43A and
43B shown in FIG. 1(b). Between two slide gears 43A and 43B provided on the output
shaft 12 and adjacent to each other in the axial direction, no bearing is provided.
[0106] The slide gear 43A has dogs 155 that are provided at an end portion opposing the
fifth speed gear 35 in the axial direction. The fifth speed gear 35 has dogs 165 that
can be meshed with the dogs 155 of the slide gear 43A. The slide gear 43B has dogs
156 that are provided at an end portion opposing the sixth speed gear 36 in the axial
direction. The sixth speed gear 36 has dogs 166 that can be meshed with the dogs 156
of the slide gear 43B. As the slide gears 43A and 43B are moved in the axial direction
from the standby position shown in FIG. 9, each of these slide gears is meshed with
one of the shift gears 35 and 36 adjacent to the each slide gear in the axial direction,
by means of the dogs. When one of the shift gears 35 and 36 is meshed with a slide
gear adjacent to the one shift gear in the axial direction by means of the dogs, power
is transmitted from the input shaft 11 to the output shaft 12 through that shift gear
and that slide gear.
[0107] The dogs 155 are aligned in the circumferential direction. The dogs 156, 165, and
166 are also aligned in the circumferential direction. The dogs 155 and 156 of the
slide gears 43A and 43B are dog teeth. In other words, the dogs 155 and 156 are formed
to protrude in the axial direction. The dogs 165 and 166 of the shift gears 35 and
36 are dog holes. The dogs 165 and 166 are concave in shape. In other words, the dogs
165 and 166 are dog holes that do not penetrate the shift gears 35 and 36 in the axial
direction. The dogs 165 and 166 may be dog holes penetrating the shift gears 35 and
36 in the axial direction. The dogs 165 and 166 may be dog teeth. In this case, the
dogs 155 and 156 may be dog teeth or dog holes.
[0108] The dogs (dog holes) 165 and 166 of the shift gears 35 and 36 have the same characteristics
as the common characteristics of the dogs 61 to 64 of the shift gears 31 to 34 described
in Eighth Embodiment. The dogs (dog teeth) 155 of the slide gears 43A and 43B have
the same characteristics as the common characteristics of the dogs 51 to 54 of the
slide gears 41 and 42 described in Eighth Embodiment. Each of the dogs 165 and 166
has a drive meshing surface 67, a coast meshing surface 68, and a movement guiding
surface 69. Each of the dogs 155 and 156 has a drive meshing surface 57, a coast meshing
surface 58, and a release guide surface 59. Each of the dogs 155 and 156 of the slide
gears 43A and 43B may have both the movement guiding surface 69 and the release guide
surface 59 as in the dog of the slider of Patent Literature 1. The dog 156 of the
slide gear 43B may not have the release guide surface 59. Each of the dogs 166 of
the sixth speed gear 36 and the dogs 156 of the slide gear 43 may not have the movement
guiding surface. The shape of each of the dogs 166 of the sixth speed gear 36 and
the dogs 156 of the slide gear 43B may be identical with the shape of each of the
dogs 66 of the shift gear 36 and the dogs 56 of the slide gear 43 of Seventh Embodiment.
[0109] With this arrangement, when shifting up to the fifth speed stage, the transmission
1 is temporarily in the double-meshed state where the two slide gears 42 and 43A are
simultaneously meshed with the two shift gears 34 and 35 through the dogs. In this
double-meshed state, a force of canceling the meshing through the dogs is generated
in the slide gear 42. When shifting up to the sixth speed stage, the transmission
1 is temporarily in the double-meshed state where the two slide gears 43A and 43B
are simultaneously meshed with the two shift gears 35 and 36 through the dogs. In
this double-meshed state, a force of canceling the meshing through the dogs is generated
in the slide gear 43A. On this account, the transmission 1 is able to seamlessly perform
shift up to the fifth speed stage and shift up to the sixth speed stage.
[0110] The slide gear 43A is spline-fitted to the input shaft 11. In the inner circumferential
surface of the slide gear 43A, one cam surface 71 and the checking groove 72 are formed
to be aligned in the axial direction. The checking groove 72 may not be formed. The
checking groove 72 is formed between the cam surface 71 and the dog 155. The slide
gear 43A makes contact with a cam biasing mechanism 80 provided on the input shaft
11. The cam biasing mechanism 80 makes contact with the cam surface 71 and the checking
groove 72. The cam biasing mechanism 80 has a spring 81 which applies an elastic force
to the slide gear 43A outward in the radial direction of the input shaft 11.
[0111] The cam surface 71 is a slope surface tilted in the radial direction relative to
the axial direction. When the slide gear 43A moves in the axial direction, the cam
biasing mechanism 80 makes contact with the cam surface 71. When the cam biasing mechanism
80 makes contact with the cam surface 71, the elastic force of the spring 81 acts
as a force of pressing the slide gear 43A in the axial direction in which the checking
groove 72 moves away from the cam biasing mechanism 80. The checking groove 72 is
formed to allow the cam biasing mechanism 80 to be fitted thereto. When the transmission
1 is not in the fifth speed stage, the cam biasing mechanism 80 is fitted to the checking
groove 72 of the slide gear 43A.
[0112] The slide gear 43B is spline-fitted to the input shaft 11. The slide gear 43B has
neither the cam surface 71 nor the checking groove 72.
[0113] The slide gears 43A and 43B are connected to the shift forks 113A and 113B, respectively.
The shift forks 113A and 113B move in the axial direction in the same manner as the
shift forks 111 and 112, as the controller controls an unillustrated shift actuator.
[Reference Signs List]
[0114] 1: transmission, 4: driving target, 5: driving source, 11: input shaft, 12: output
shaft, 31, 32, 33, 34, 35, 36: shift gear, 40: slider having cam surface (slide gear
having cam surface), 41, 42: slider (slide gear, switching slide gear), 43, 43A, 43B:
slider (slide gear), 45: gear tooth surface, 46: recess, 47: protrusion, 71: cam surface,
80: cam biasing mechanism, 81; spring, 110, 111, 112, 113: shift fork, 141, 142, 143:
moving range, C11: axial center of input shaft, C12 axial center of output shaft